The invention relates to nuclear magnetic resonance (NMR) spectroscopy, and in particular to systems and methods for regulating coil temperatures in NMR spectrometers.
Nuclear magnetic resonance (NMR) spectrometers typically include a superconducting magnet for generating a static magnetic field B0, and an NMR probe including one or more special-purpose radio-frequency (RF) coils for generating a time-varying magnetic field B1 perpendicular to the field B0, and for detecting the response of a sample to the applied magnetic fields. Each RF coil and associated circuitry can resonate at the Larmor frequency of a nucleus of interest present in the sample. The direction of the static magnetic field B0 is commonly denoted as the z-axis or longitudinal direction, while the plane perpendicular to the z-axis is commonly termed the x-y or transverse direction. The RF coils are typically provided as part of an NMR probe, and are used to analyze samples situated in sample tubes or flow cells.
Some NMR systems employ a cryogenically-cooled NMR probe. A cryogenic fluid such as liquid nitrogen or liquid/gaseous helium conductively cools NMR circuit components such the NMR RF coils, circuits and preamplifiers. The sample of interest may be held at room temperature or at a different temperature than the cryogenically-cooled circuit components. Examples of U.S. Patents describing cryogenically-cooled NMR probes include U.S. Pat. Nos. 6,838,880, 6,677,751, 5,889,456 and 5,739,689.